1. Field of the Invention
The present invention relates to a Portable Voltage and Current (VI) Probe for attachment to at least one transmission line.
2. Discussion of the Background
In the fabrication and processing of semi-conductor wafers, such as silicon wafers, a variety of different semiconductor equipment and processes can be utilized. For example, wafer processing techniques are known in the art and may include, for example, photolithography, ion beam deposition, vapor deposition, etching, as well as a variety of other processes.
In one method of wafer processing, plasma generators are used to process a wafer, for example by etching a layer formed on the surface of the wafer. In employing this technique, electrical power is coupled to the plasma generator from an electrical source. Typically, the electrical energy has a frequency in the radio frequency (RF) range. Control of the process is performed in part by measuring and monitoring the RF voltage and the RF current components of the RF power source coupled to the plasma generator. It is generally desirable to obtain the voltage and current measurements as close to the plasma generator as possible in order to obtain a true representation of the actual RF voltage and current entering the plasma generator with minimal effects on the transmission line. Therefore, a common practice for measuring RF power is to install a sensor for monitoring current and voltage in series with the transmission medium coupling the RF power to the plasma generator.
However, RF monitors can disrupt the plasma process or may fail to obtain accurate indications of the ongoing plasma process. Furthermore, the monitor itself may affect the RF signal due to reflections, for example. Due to different system configurations, it is desirable to be able to measure the RF power at various locations along the transmission line using a portable probe as opposed to using a probe which is integrated into the transmission line.
Consequently, there exists a need for a portable VI probe for monitoring a source of RF electrical power, which minimally intrudes in the RF transmission line in which the probe is placed.